Kraft Black Liquor as a Carbonaceous Source for the Generation of Porous Monolithic Materials and Applications toward Hydrogen Adsorption and Ultrastable Supercapacitors

Abstract

High internal phase emulsions (HIPEs) have templated self-standing porous carbonaceous materials (carboHIPEs) while employing Kraft Black Liquor, a paper milling industry byproduct, as a carbon precursor source. As such, the starting emulsion has been prepared through a laboratory-made homogenizer, while native materials have been characterized at various length scales either with Raman spectrometry, X-ray diffraction (XRD), mercury intrusion porosimetry, and nitrogen absorption. After thermal carbonization, specific surface areas ranging from ∼600 m 2 g −1 to 1500 m 2 g −1 have been reached while maintaining a monolithic character. Despite a poor graphitization yield, the carbonaceous materials offer good electronic transport properties, reaching 31 S m −1 . When tested toward energy storage applications, the native unwashed materials revealed a hydrogen storage of 0.07 wt % at 40 bar and room temperature (RT), while hydrogen retention is reaching 0.37 wt % at 40 bar and RT for the washed sample. When employed as supercapacitor electrodes, these carbonaceous foams are able to deliver high capacities of ∼140 F/g at 1 A/g, thereby matching the ones obtained from a commercial carbon reference, while additionally providing a restored remnant capacity of 120 F/ g at 2 A/g over 5000 cycle numbers.

3D Carbonaceous Foams Derived from High Internal Phase Emulsion for Energy Applications

“…More recently, Poupart et al proposed a new biosourced PolyHIPE from Kraft Black Liquor (KBL), a waste product of paper milling industry, as a carbon foam precursor. [38] This product is an alkaline aqueous solution made [36] (Reproduced from reference [36] with permission Copyright 2021, Elsevier) of degraded lignin and hemicellulose that can be polymerized and crosslinked with epichlorohydrin within a HIPE. The resulting low density PolyHIPE (1.34 g mL À 1 ) exhibit a typical open and hierarchical porosity of 60 % with an average window diameter of 0.4 μm.…”

“…As described in section 2.1, Poupart et al developed a biobased CarboHIPE resulting from the emulsion-templated BKL PolyHIPE. [38] After testing their material performances as an electrode material for supercapacitors, they also evaluated its capacity to store hydrogen. Thanks to its high specific capacitance of 1550 m 2 g À 1 and its hierarchical porosity of 71 %, the carbon foam was able to store up to 0.37 H 2 wt % at 40 bars and room temperature.…”